A surface of the human skin is protected by a keratin layer, and among constituents of the keratin layer, keratinocyte lipid forms a layer structure and contributes to maintaining basic functions of the skin.
The keratinocyte lipid is formed with ceramides, cholesterol, free fatty acids and the like. Among these, ceramides play a central role in water retention and barrier function of the keratin layer, and it has been known that, when the ceramide content decreases in the keratin layer, a protective barrier function of the keratin layer deteriorates and various skin diseases become worse.
Meanwhile, it has been reported that, when the keratin layer is damaged by skin aging or external stimuli, and a ceramide content decreases in the keratin layer, ceramides may be supplemented from the outside to restore the skin to a normal condition by restoring the skin's lamellar structure. In view of the above, development for cosmetic compositions including ceramides with the purpose of restoring and maintaining a skin barrier function and enhancing moisturizing power has been actively progressed.
Such ceramides are extracted and used from various animals, plants and microorganisms. However, ceramides present in these animals and plants and microorganisms are extremely small in quantities, and thereby have problems in that extraction is difficult and production costs are high. In addition, nature-derived ceramides have very low solubility for materials such as solvents commonly used in cosmetics, and are difficult to be included in a product in amounts sufficient to exhibit their effects.
As a result, studies on pseudo-ceramide compounds that may replacing natural ceramides have been made. As one example, pseudo-ceramide compounds disclosed in Korean Patent Application Laid-Open Publication No. 2014-0070474 may be included. As above, research and development on pseudo-ceramides having more improved properties while having similar structures and effects to natural ceramides have been consistently required.